1. Field of the Invention
The present invention relates to a printing plate, and more particularly to a printing plate and a mirror thereof, which have different surface structures.
2. Description of the Prior Art
Conventionally, a photolithography process has been widely used in manufacturing electronic devices. However, the photolithography process increases an initial investment cost due to the use of expensive equipment, and decreases economic efficiency because an expensive mask is required in large quantities according to device integration.
Accordingly, various inexpensive printing methods for forming various patterns on a substrate based on high-resolution printing technology have recently been in the spotlight. Among them, a solution transfer printing method using gravure printing or micro-contact printing can efficiently form a thin film on a large-area substrate by transferring a solution onto the substrate, and thus has been actively studied and applied to practical use in recent years.
The solution transfer printing method using gravure printing or micro-contact printing uses the following two ways to obtain different surface energy:
The first way is to fabricate a printing plate, which itself is made of a material with low surface energy. The second way is to introduce another layer with low surface energy on the surface of a fabricated printing plate.
However, the first way has a problem in that there is a limitation on the material with low surface energy.
The second way has problems in that a chemical substance must be additionally used to apply an organic material with low surface energy all over the surface of a printing plate, it is difficult to maintain the surface energy of the organic material layer with an increase in the use frequency and with the passage of time, and the durability of a substrate must be taken into consideration. Further, the second way is disadvantageous in that the processing time is long because an additional surface treatment process is involved, and the overall processing time is also lengthened because additional time for preprocessing and post-processing is required for selective surface treatment (Ling et al., U.S. Pat. No. 7,687,007 B2 (2010)).
To solve these problems, in the study by K.-H. Lee et al. (“Solution processable micron- to nanoscale conducting polymer patterning utilizing selective surface energy engineering”, Organic Electronics, article in press (2009)), a substrate was subjected to surface treatment by applying a photolithography process to a typical bottom-up printing technique such that the substrate selectively has low surface energy, and an organic material was used as the surface treatment material. However, together with a durability problem with the use of the organic material as a partition wall, there is a problem in that the overall processing time is lengthened due to the addition of the photolithography process.
In the study by W.-K. Huang et al. (“Organic selective area patterning method for microlens array fabrication”, Microelectronic Engineering 83 (2006)), micro-contact printing was used for selective surface treatment, and a substrate was provided with different surface energy by dipping the entire mold in an organic material solution with low surface energy, taking out the mold from the organic material solution, and then transferring the organic material, which sticks to the mold portion to be contacted with the substrate, onto the substrate. In this case, however, the mold may be contaminated because the mold itself is dipped in the organic material solution with low surface energy, and the selective surface treatment on the substrate requires a process of transferring the organic material through micro-contact printing.